Cut-off valve of steam-engines



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J. M. COLMAN, OF MILVAUKEE, VISCONSIN.

CUT-GFF VALVE OF STEAM-ENGINES.

Specification of Letters Patent No. 22,164, dated November 30, 1858.

To all whom t may coacem:

Be it known that I, J. M. COLMAN, of Milwaukee, in the county of Milwaukee and State of lisconsin, have invented a new and useful Improvement in Variable Cut- Offs for Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a longitudinal vertical section of the valve chest of an engine showing also the application of my cut-o1 in connection with a governor. Fig. 2 is a top view of one of the slide valves with its cut-off Valve attached.

Similar letters of reference indicate the same parts in both gures.

This invention consists in the employment of flap valves, combined in the manner here inafter specified with sliding induction valves, for the purpose of cutting oli steam suddenly from said induction valves at such point in the stroke of the engine as may be determined by a governor or by any suitable adjustable contrivance, whereby the former.

are rendered capable of cutting oif steam from the slide valves suddenly at such point in the stroke of the engine as may be determined by a governor or by other adjustable contrivances as hereinafter described.

To enable others skilled in the art to make and use my invention7 I will proceed to de scribe its construction and operation.

A,`is the steam chest or valve chest.

a, a, and a, a, are the valve seats containing the steam ports 0, a', communicating with the cylinder, and the exhaust portsl (Z, d', leading to the exhaust pipe, the arrangement of said ports being the same as is common when separate slide valves are used for induction and eduction to and from each end of the cylinder.

B, B, are the slide valves, one for each end of the cylinder, constructed as such valves usually are, but with the addition of shields ZJ, b', to the outer side of each, to form passa-ges d, d', outside the valve as usually constructed; said passage terminating in the principal or usual faces of the valves which t theseats a, a, and a', a', and in faces e, e', which serve as seats to two flap valves C, C, which are hinged to the slide valves at y, f, and which are arranged Ito close the passages (Z, d. The openings of the slide valves are of a size and form corresponding with the steam ports c, C,' and the seats a, a, and a, a, of said valves extend a dist-ance beyond the outer sides of said ports equal to the width of the ports.

rlhe flap valves are each provided with a pointed arm or lifter g, which points toward the back of the chest, and in said back of lthe chest, over the two pairs of steam and exhaust ports, there are two stuffing boxes y', y", through which pass rods z', z', at the extremities of which are jointed toes 7L, t, which are beveled on the sides farthest from the ends of. the steam chest and fitted to their guides in the back of the steam chest in such a manner as to permit them to swing from a vertical position toward the nearest ends of the steam chest, but not in the opposite direction. The rods i, z', are connected with the ends of two levers le, c, which work on fulcra Z, Z, outside the steam chest and whose opposite ends are connected with a governor Gr, in such a manner that a l:liminution of velocity of the said governor will cause the rods z', z", to project their toes farther into the steam chest and an increase of velocity to produce an opposite effect.

The two slide valves are connected together by a rod m, and derive a motion such as is generally imparted to a pair of short slide valves from an eccentric on the main shaft of the engine connecting with a rod a, which passes through one end of the valve chest. The movement of the slide valves causes their respective Hap valves C, C, to be opened as the former respectively move in a direction to open their respective ports by the arms g, g, striking the toes 71., L; but as the slide valves move in the opposite direction the toes t, it, swing and permit the arms g, g, to pass them. The valves C, C, close by gravitation with a tripping motion as the arms g, g, escape the toes L, L, in moving in the direction first above mentioned, and thus cut off the steam suddenly, as the only passages for the steam from the valve chest to the cylinder are those (Z, d. The escape of the valve arms and cutting off the steam take place sooner or later in the stroke of the engine, according as the toes 7L, and h', are projected less or more into the valve chest. During the rst part of the stroke of the valves in either direction, the steam which fills the steam chest passes under the shield Z), or ZJ, of the slide valve B or B, Whose steam port c, or c, is to be opened by that stroke, and into the passage (l, or d, oi said valve, so that the valve C or C', belonging to the said slide valve is exposed to the steam both above and below, and consequently n equilibrio, and this Continues to be the oase until the time for admitting the steam to the cylinder, and hence When the valve arm g, strikes the toe 7L, or L, the valve C, or G, opens Without diiiieulty; but as soon as it leaves its seat and the passage d, or V begins to communicate With the Cylinder, the lower opening of said passage is closed to the steam chest by the shield Z), or of the valve oom-- ing on the valve seat. This Cutoff is capable of cutting olf the steam at any point in the first half of the stroke of the piston. The variation, effected by the governor in the manner hereinbefore speeied serves to control the velocity of the engine; but the toes h, 7L', may be adjusted, if desired, Without a governor, to out otl' at any fixed point in the stroke.

The invention is represented applied to a horizontal engine, but it may be applied to a vertical engine, With so very triiling a change in the mode of application of one of the flap valves as Will readily suggest itself, to make it close by gravitation; or by applying a spring to make the flap valve which Would stand above its hinge self-closing, the mode of applying both valves shown in Fig. 1 may be used in an upright as Well as in a horizontal engine, either with one or two slide valves.

What I claim as my invention, and desire Ato secure by Letters-Patent, is

The arrangement and combination of the flap valves C C', valves B, B', jointed toes /L 7L', rods z' z, levers 7c 71;, and governor G, as and for the purposes herein shown and described.

J. M. COLMAN.

Witnesses:

Gr. CAMPBELL, Gr. R. SMITH. 

